What are some money tips once you have a credit card?, and what are some things i should consider at 20 ?

1. Don't max it out. 

2. Pay it off in full each month. 

it's easy to spend a lot of money on subscription services.

Unless you are planning on living at home forever, not buy your own car, or pay your own health/car insurance....

Spending 25% of your income on subscription services is really stupid. 

Pay the with the card and pay it off each month. When they raise your available credit, and by paying it off each month, your score should go up.

pay your phone bill in full every month. ALWAYS ask what the finance charge percentage is on all credit cards before you get one and use it. those charges add up to a lot. for instance if the finance charge is 22% and you owe $100. they suck you in by saying you'll only have to pay $10 a month, but the bank also charges you $22 in finance charges. you'll end up paying back $500 for the $100 you put on that card. keep your credit score high, 750+. that way you'll be eligible to use 0% for a year finance charge cards. when the year is up, roll over the amount you owe to another 0% for a year finance card. that way you never pay finance charges. I did it for years until I paid off all my credit card debt.   

Having the credit card is good in the long run, but you don't have to change your spending behavior.  Using it once every few months and paying it off on time to avoid interest is just as good as using it daily.  Until you are used to managing credit, you shouldn't rush into making it your primary form of payment.  Stay the course you're on.